1. Field of the Invention
The present invention relates to an antimicrobial agent, in particular, an antimicrobial agent which is prepared from a propanediol mono-β-hydroxycarboxylic acid ester which is an ester composed of propanediol and β-hydroxycarboxylic acid.
2. Description of the Related Art
In recent years, skin irritation caused by paraben has become a problem and it is desired to reduce the compounding amount of this substance for safety sake. As a technique for reducing or excluding antiseptic bactericides such as paraben, benzoic acids and salicylic acids which are used as antiseptic bactericides of cosmetic products and pharmaceutical products, there has been disclosed an antiseptic bactericide which is prepared from 1,2-alkanediol (refer to Patent Document 1). However, if 1,2-alkanediol such as 1,2-octanediol is used solely as an antiseptic bactericide, compounding a large amount of this substance might be required in order to obtain sufficient effects. Further, 1,2-alkanediol has a distinctive odor derived a raw material. Thus, it is desired to develop an antiseptic bactericide which is capable of exerting sufficient antiseptic and bactericidal effects.
It is also known that an ester of hydroxycarboxylic acid exhibits antimicrobial actions. For example, there have been disclosed an antimicrobial agent which is characterized in containing an α-hydroxycarboxylic acid alkyl ester as an effective component and a cosmetic product which contains an optically active α-hydroxycarboxylic acid alkyl ester as an antimicrobial component (refer to Patent Document 2).
However, any of the hydroxycarboxylic acid which is a constituent component of the above-described hydroxycarboxylic acid ester is that having a hydroxyl group at the alpha position and there is no disclosure about β-hydroxycarboxylic acid having a hydroxyl group at the beta position. Further, disclosed is an alkyl ester with monovalent alcohol having one hydroxyl group, and there is no disclosure about a monoester with polyvalent alcohol such as propanediol. Further, there has been a problem with a hydroxycarboxylic acid alkyl ester that it has a lower affinity to water than a monoester made up of hydroxycarboxylic acid and polyvalent alcohol due to having less hydroxyl groups.
Patent Document 1: Japanese Published Unexamined Patent Application No. H11-322591
Patent Document 2: Japanese Published Unexamined Patent Application No. H8-325107